captioning sponsored by cbs this is the "cbs evening news" with scott pelley. >> pelley: good evening. whether the u.s. enters the war in syria appears to be up to the dictator bashar al-assad. on monday, david martin reported that the assad regime had given orders to prepare chemical weapons for possible use to put down the revolt that has been raging in that country for more than a year and a half. president obama said the use of these weapons of mass destruction would be totally unacceptable. well, tonight, david has new intelligence to report, and we have three stories on the breaking news in syria. we'll start with martin at the pentagon. >> reporter: u.s. intelligence so far has not detected any signs syria is loading chemical weapons on to aircraft, but defense secretary panetta said it appears the embattled assad regime is preparing to do just that. >> there is no question that we remain very concerned, very concerned that as the opposition advances, in particular on damascus, that the regime might very well consider the use of chemical weapons. >> reporter: monitoring of syri